Hydrogen peroxide bleaching solution and method

ABSTRACT

Cotton greige goods are simultaneously scoured, desized and bleached in less than four minutes by immersion in a heated bleach solution consisting of hydrogen peroxide characterized as being essentially free of heavy metal ions or water, and absolutely no other additives, except hydroxide to maintain the pH of the solution between 10 and 14; the solution being maintained in a non-metallic container.

United States Patent 1191 Katz 1 1 HYDROGEN PEROXIDE BLEACHING SOLUTION AND METHOD [76] Inventor: Jerome Katz, P.O. Box. 1544,

Brighton, NY. 14603 [22] Filed: Dec. 6, 1972 121] App]. No: 312,637

[52] US. Cl.. 8/111; 162/78; 252/95; 252/103; 252/186 [51] Int. Cl. D06L 3/02 [58] Field of Search 252/186, 95; 8/111; 253/103; 162/78 [56] References Cited UNITED STATES PATENTS 3,127.233 3/1964 Lowes 8/111 3,142.53] 7/1964 Rogers 8/111 [451 Nov. 11, 1975 3.382.149 5/1968 HOh 1. 8/111 3.514.247 5/1970 Lawes et a1 252/186 3.528.115 9/1970 Lawes 252/186 Prinmry Examiner-Benjamin R. Padgett Assistant Examiner-Irwin Gluck AIIUI'HG), Agent, or Firm-Clarence A. OBrien & Harvey B. Jacobson [57} ABSTRACT Cotton greige goods are simultaneously scoured, desized and bleached in less than four minutes by immersion in a heated bleach solution consisting of hydrogen peroxide characterized as being essentially free of heavy metal ions or water, and absolutely no other additives, except hydroxide to maintain the pH of the solution between 10 and 14; the solution being maintained in a non-metallic container.

10 Claims, 2 Drawing Figures US. Patent Nov. 11, 1975 3,918,898

BLEACH OUT ,BLEACHING,

SCOUR AND DESIZE m OUT IN OUT I I 28 I I r r RINSE E YGZII j ijii OUT 0 i i RINSING 30 i i i SCOUR AND 26 BLE I HEATER TSTEAM m o T U FIGJ TANKS C i |4,|e,|a

STORAGE 36 TANK 32' H o m HYDROGEN PEROXIDE BLEACHING SOLUTION AND METHOD The present invention relates to bleaching of cotton goods and to bleaching solutions for such use.

The invention is especially suitable for peroxide bleaching of cotton greige goods either in batches or continuously and is effective to simultaneously scour, desize and bleach such goods in one operation.

Bleaching of cotton goods with hydrogen peroxide is in general use at the present time. Reference may be had to the following article for a historical survey of the development of hydrogen peroxide bleaching:

Lynn, "Peroxide Bleaching of Textiles," American Dye Stuff Reporter, Oct. 5, I969, pps 20-25; Easton, Bleaching Cottons with Hydrogen Peroxide," American Dye Stuff Reporter, July 9 1962, pps 23 to 30. The patent literature also contains references to bleaching with various peroxide type compounds, see US. Pat. Nos. 3,553,140; 3,481,827; 3,528,115; 3,350,160; 3,343,906; 3,280,039; 3,156,654; 3,034,851; 3,012,978; 2,886,532; 2,868,615; 2,828,181; and 2,720,440, as well as the patents cited in the abovereferenced articles, and in the above-referenced patents. Solutions of hydrogen peroxide for simultaneously scouring and bleaching of cotton goods are described in US. Pat. No. 3,514,247.

Proposed peroxide bleaching methods and bleach solutions are complex in their chemistry and in their implementation in that they utilize contradictory and opposing elements and techniques in order to stimulate bleaching action and then to stabilize or control such action. For example, many peroxide bleaching systems utilize metallic vessels, and in addition some systems add metal ions to further decompose the hydrogen peroxide in an effort to speed the bleaching and reduce bleaching time. In direct opposition to the foregoing activation techniques, the conventional bleaching systems involve the use of stabilizers. Silicates are usually used as stabilizers. However, chelating agents may also be used. The silicates and other additives have serious drawbacks, such as the production of turbid baths that deposit sediment on the goods, and as well, increase the problem of pollution control. The additives, and particularly the heavy metal ions which they impart or are otherwise present in known bleach solutions, can also cause discoloration of the bleached goods. Even when pure hydrogen peroxide is available, say with iron concentrations of around 0.00005 percent, the practice in conventional bleaching processes is to add tap water containing phosphates and other heavy metal ions in the course of dilution of the peroxide to working concentration, besides the other above mentioned additives. It is believed that discoloration is produced by the process of oxidative coupling of the metal to the complex colored molecules of the fiber as it is bleached. Thus the more complex the bleach bath is made by the addition of stabilizers, chelating agents, and additional metal ions, the higher the probability of oxidative couplings and the higher the probability of discoloration. It has been found through experiments that tiny reddish specks, sometimes called motes" in the bleaching trade, occur in the presence of a metallic system. Sometimes these motes can be eliminated by extending the bleaching time (viz., time in solution). However, additional bleaching time tends to weaken fabric and is undesirable. ln addition, the complex bleach solutions reject or reduce the effect of flourescent brighteners. [t

has been found that such brighteners become oxidized and rendered non-flourescent in complex conventional bleach systems.

It is therefore an object of the present invention to provide an improved method for bleaching of cellulose based fibers, especially cotton goods, wherein the foregoing difficulties and disadvantages are substantially eliminated.

It is a further object of the present invention to provide an improved bleaching solution which substantially obviates the above-mentioned drawbacks and disadvantages of conventional solutions.

It is a still further object of the present invention to provide an improved process for the bleaching of cotton goods which may be implemented at lower cost than the heretofore existing processes.

It is a still further object of the present invention to provide an improved process for bleaching cotton goods wherein the chance of damaging and discoloration of the goods is reduced.

lt is a still further object of the present invention to provide an improved peroxide bleaching solution which may be implemented in a bleaching method for simultaneously scouring, desizing and bleaching cotton goods.

It is a still further object of the present invention to provide an improved method of peroxide bleaching of cotton goods which is capable of bleaching the goods to a commercially required degree of whiteness in less than 3% minutes.

It is a still further object of the present invention to provide an improved bleaching solution and bleaching process using a peroxide bleaching system wherein flourescent whiteners may be used and the use of such whiteners is promoted instead of retarded by the action of the system.

It is a still further object of the present invention to provide an improved process for peroxide bleaching of cotton goods which reduces deposits in the course of the process, thus simplifying and reducing the expense of pollution control.

Briefly described, a bleaching system in accordance with the invention utilizes hydrogen peroxide in aqueous solution in non-metallic containers; the solution not requiring, and consisting entirely of the absence of, any additives or stabilizers. The goods to be bleached are immersed in the solution and simultaneously scoured, desized and bleached in less than 3% minutes when the solution is heated to temperatures in the range of F to 212F. More particularly the solution may include hydrogen peroxide, characterized as having no heavy metal ions, water and hydroxide, preferably in the form of sodium hydroxide sufficient to raise the solution pH to the range from 10 to 14; the range of 10.5 to 13.5 being preferable. The hydrogen peroxide is preferably in the range 1 to 10 percent by volume of the volume of the solution. More specifically, the process may be carried out with the aid of a plurality (e.g., 3) of containers, each of which is non-metallic or at least has the portion thereof in contact with the bleach solution of nonmetallie material, such as glass, plastic, or a polymeric material. The solution in the containers is preferably heated to a temperature within the range of 160F to 212F. The goods are successively immersed into the solution in each of the containers; the total immersion time being less than 3% minutes. The resulting product is scoured, desized and bleached. If desired, the bleaching solution may contain a flourescent whitener. It will be observed that bleaching is carried out in non-metallic containers, and does not require stabilizers, chelating agents or any other additives or the like. It has been found that deposits as a result of the bleaching process are minimized, thus making a continuous flow of the bleaching solution with suitable filtering practicable. The bleaching solution is thus recirculated and pollutants, contaminants and other deposits removed without introducing the bleach solution or any expended bleach solution into the environment.

The foregoing and other objects and advantages and features of the present invention will become more readily apparent from a reading of the following specification in connection with the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating a bleaching system and method in accordance with the invention; and

FIG. 2 is a schematic typing diagram illustrating how the bleaching solution is recirculated in the system illustrated in FIG. 1.

Referring particularly to FIG. 1, the cotton greige goods to be bleached is fed off a roll into and through a tank or container 12. The container 12 like the other containers in the system are of non-metallic material. Glass or glass-lined metallic (say steel) containers are suitable. The containers alternatively may be of plastic material. Of the plastic materials, hard polypropylene, which is a polymeric material, is preferable. Deionized water is circulated through the tank 12. The water may be deionized by passing the water through a deionizer and demineralizer, VWR Scientific of Rochester, New York, Cat. No. 24804-002 "Deeminizer," Crystal Lab. demineralizer being suitable. The Deeminizer" produces mineral free water with an ionic content of less than 1 ppm from ordinary tap water. It removes both cations and anions and dissolves solids. The water is passed through the Deeminizer until its meter reads in 0-50 ppm as sodium chloride. When the meter reading exceeds 25 ppm, it is desirable that the cartridge be replaced.

The dipping of the goods into the deionized water removes those impurities which would otherwise build up in a continuous bleaching system as is illustrated in FIG. 1. In effect, the dipping step in the process aids in removing impurities and in effect stabilizes the bleaching process. In the event that a batch or other non-continuous process is used, then the step of dipping as in the container 12 may be omitted.

After passing through the clipping container 12, the goods are passed to a first of three bleaching, scouring and desizing tanks or containers 14, 16 and 18. The bleaching solution is circulated through each of these containers, preferably through a continuous re-circulating system which will be described hereinafter in connection with FIG. 2. Each of the bleaching containers is non-metallic, at least on the surfaces thereof that contact the bleaching solution. As was discussed above, plastic, preferably polymeric (e.g., polypropylene) containers, or container linings, may be used. The total bleaching time is approximately 3 h minutes. Thus, the rate of travel of the goods is such that the goods remain in each tank approximately 1 minute and I0 seconds. The bleaching solution may be made up and consist of the components to be described in the following examples. Briefly, the solution consists of: hydrogen peroxide which is characterized as having no heavy metal ions, electronic grade hydrogen peroxide such as may be procured from J. T. Baker Company of Phillipsburg, NJ. H 0 30 percent by weight, Catalog No. 2189 electronic grade H 0 (This material may be obtained also from VWR Scientific Company of Rochester, N.Y.); water which is preferably deionized water; and a hydroxide in sufficient quantity to maintain the pH of the solution in an appropriate range (say ID to 14). There are no other additives, stabilizers, or agents used in the solution.

Each of the tanks l4, l6 and 18 is equipped with a heater 20, 22 and 24, which may be a steam operated heat exchanger for maintaining the bleaching solution in a temperature range from I60F to 212F.

After passing through the last tank 18, the goods are passed through a rinsing tank 26, through which rinse water is circulated.

After rinsing, the goods are dried in a dryer 28 which may be of a heated air-flow type. The goods are finally wound on a take-up reel 30. Alternatively, the goods may be continuously fed to the next process stage such as dyeing or cutting into pieces for further manufacture.

Inasmuch as the scouring, desizing and bleaching processes carried on in each of the tanks results in a few deposits or fallout as in conventional systems, the system shown in FIG. 2 may be used for recirculating and pollution control. The solution is stored in a storage tank 32 to which additional solution may be added to make up for evaporation and depletion, peroxide content, as well as to maintain an adequate pH. Automatic sensors may be used to provide for the introduction of makeup solution so as to maintain proper bleaching solution strength (in terms of peroxide content) and pH. The solution is pumped by means of a pump 34; the pressure and flow of the solution being controlled by a valve 36. The valve 36 is connected by piping to the inlet pipes of each of the tanks l4, l6 and 18. The outlet pipes from the tanks then are connected together and are piped to a filter 38, which may be a mechanical filter such as a screen. Sufficient back pressure is maintained by another pump 40 and a control valve 42. The filtered solution is fed back into the storage tank to complete the recirculation system. After a period of use, the filter may be cleaned and the filtrate removed to a precipitating tank without polluting the environment in any way whatsoever.

Although a continuous process is described in connection with FIGS. 1 and 2, it will be appreciated that a batch or single tank process may be used in accordance with the invention. In that event the goods are maintained in the tank, either in strand or rope form for the bleaching period (the 3 to 3% minutes). Thereafter the goods are withdrawn from the tanks, rinsed, dried, and are ready for use in other steps of the textile process.

The following methods may be used in the examples listed below to provide hydrogen peroxide which is essentially free of heavy metal ions:

Hydrogen peroxide can be made in a pure form essentially free of heavy metal ions by oxidizing in the liquid phase isopropyl alcohol or another secondary alcohol having 3 to 6 carbon atoms with oxygen or a gas containing oxygen at a temperature between C and C under a pressure which is at least sufficient to allow the alcohol to remain in the liquid phase as described in US. Pat. No. 3,592,776, Fletcher et al, issued July 13, 1971. Since in this method the only catalyst used is hydrogen peroxide itself or a non-metallic TABLE BAKER NO. 2186 Assay (H,O,) 31.4%

Iron (Fe) 0.00002% Heavy Metals (as Pb) 0.001303% Ammonium lNH.) 0.0005% Sulfate (S0,) 0.0002% Phosphate (P 0.0000796 Nitrate (N0 0.00007% Chloride (Cl) 0.000l% Free Acid (as H,SO 0.000470 Residue after evaporation 0.0006% In the event that organic impurities boiling at a higher temperature than H 0 are present, then they can be removed by counter-current, continuous, liquidliquid extraction methods as described in US. Pat. Re. No. 25,114 original US. Pat. No. 2,949,343 by Hood et a1.

Another hydrogen peroxide which can be used is available from the Shell Oil Co., their 30 percent electronic grade which has the following analysis: Heavy Metal (as Pb) 0.001 percent; iron (as Fe) -0.00005 percent; Silicon 0.00005 percent; Nickel 0.000002 percent: Chromium 0.000002 percent.

The aforementioned Fletcher patent uses a method of reacting the H 0, with urea to form a H O, urea adduct that can be easily precipitated from the reaction mixture and reacted with an extracting solvent such as acetone that decomposes the adduct and precipitates the urea. This leads to a solution of H 0, in acetone that is extracted with more acetone and finally the acetone is removed by distillation.

The sodium hydroxide used is.also low in heavy metal ions, ACS, Reagent grade NaOH; Fisher Scientific Catalog No. S-3l8 is suitable. This certified ACS NaOH contains 0.0003 percent iron.

The following are examples of procedures whereby the bleaching solutions suitable for use in the above described bleaching systems may be prepared:

EXAMPLE 1 1.4 quarts of hydrogen peroxide (30% by weight) were added to 28 quarts of water (distilled water or de ionized water, the latter being preferred; the water being passed through the Deeminizer so long as the meter reads less than 3 ppm) to which sufficient sodium hydroxide was added to increase the pH of the solution in the range from 10.5 13.5; 11.5 being preferred. The pH being measured by a model 37A Coleman portable pH meter using a Corning Catalog No. 47022 glass electrode and a Corning Catalog No. 476002 reference electrode, calomel. with fiber tip. in dilute aqueous hydrogen peroxide solutions a pH reading as measured above does not differ substantially from the "true aqueous pH." The solution was placed in a single non-metallic (glass) tank and heated to 190F. Cotton greige goods in the form of cotton knit fabric were de-sized, scoured and bleached to commer- 6 cial brightness after immersion in the tank for 3 minutes and 30 seconds. The hydrogen peroxide was electronic grade hydrogen peroxide obtained from .I. T. Baker. (Source mentioned earlier).

EXAMPLE 2 Hydrogen peroxide 30 percent electronic grade (or H.,O essentially free of heavy metals) procured from the source mentioned in Example 1 in the amount of 1.4 quarts thereof was added to 28 quarts of de-ionized water.

Sufficient sodium hydroxide was added to the solution to increase the pH to 11.75.

The solution was used in a single tank made of glass. The solution was heated to C. Cotton greige goods in the form of cotton knit textile was scoured, desized and bleached after immersion in the tank for 3 minutes and 20 seconds. Thereafter the goods were rinsed and dried and had commercially-acceptable brightness.

EXAMPLE 3 A bleaching solution was made by adding 4.2 quarts of hydrogen peroxide (30% electronic grade procured from the source mentioned in Example 1) to 84 quarts of de-ionized water, the water being deionized by the method set forth in Examples 1 and 2. Sufficient sodium hydroxide was added to the solution to increase the pH to 12. The pH was measured in the same manner as set forth in Example 1. The solution was placed in 3 tanks as shown in FIG. 1 and heated to 85C. Cotton greige goods were continuously passed through the tanks. Total process time of 3 minutes and 15 seconds. After the goods were rinsed and dried, they had commercially acceptable brightness.

EXAMPLE 4 A bleaching solution was made up in Example 1. To this solution was added a flourescent whitener. The solution was heated to 85C. The flourescent whitener was procured from Geigy Company of Ardsley. New York, and Surpass Chemical.

WHlTENER EXAMPLE To 10 gallons of essentially pure H,O solution containing 5 percentby volume of 30 percent by weight H 0 at pH 1 1.5 i 0.5 pH units at a temperature of approximately F was added any of the whitener solu tions set forth in Examples (a), (b), (c) or (d). At the present time the whitener of Example (c) is preferred.

Example (a) Geigy Company whitener known as Tinopal AMS and RBS 5 ounces Tinopal AMS 0.4 ounces RBS 2% ounces Ascorbic Acid 1 ounce Fluorazine TB Fluorazine TB available from Surpass Chemical, Albany, New York, being used.

Example (b) ounce AMS 8 ounces Fluorazine TB V2 ounce Ascorbic Acid Example (c) (The Preferred Embodiment Whitener) 8 ounces Fluorazine TB Example (d) Sufficient Fluorazine TB to provide 86 ml percent by volume in the solution The goods were immersed in the tanks for 3 minutes and 15 seconds. The goods were cotton knit fabric and they were simultaneously scoured, desized, bleached and whitened to a high degree of brightness.

EXAMPLE By way of comparison, a solution of commercial grade hydrogen peroxide (50 milliliters of 30 percent hydrogen peroxide) was added to 950 milliliters of water. Sufficient sodium hydroxide was added to increase the pH to l l.5. The solution was poured into a stainless steel tank. The solution in the tank was heated to 85C, as was the case for each of the solutions described in Examples l through 4 above. The goods were left in the tank for approximately 3 and '15 minutes. As compared to the whiteness level obtained with Example l, 2 and 3, the whiteness level was significantly lower by observation. The whiteness level lowers by an additional degree of whiteness than the goods bleached in accordance with Example 4. In other words, Example 4 had the highest level of brightness. Examples l, 2 and 3 being the next highest level of brightness, and Example 5 the lowest level of brightness.

In each case the goods bleached were the same cotton greige goods in the form of a knit cloth.

From the foregoing description it will be apparent that there has been provided an improved bleaching method and system and an improved bleaching solution. Variations and modifications in the herein described method and solution will undoubtedly present themselves to those skilled in the art. Accordingly, the foregoing description should be taken merely as illustrative and not in any limiting sense.

What is claimed is:

l. A continuous process for scouring, desizing and bleaching cotton greige goods comprising the steps of:

a. immersing said goods in a deionized water bath to remove impurities from said goods;

b. immersing said goods for a time sufficient to achieve commercial brightness but less than about three and one-half minutes in an aqueous solution having a temperature in the range from l602 l 2F and consisting of from 1 to 10 percent by volume hydrogen peroxide, water and sufficient hydroxide to adjust said solution to a pH in the range from lO-l4, said solution being substantially free of heavy metal ions and maintained out of contact with all metals while said goods are immersed therein;

c. continuously cycling a portion of said solution through a filtration means to remove solid impurities therefrom while maintaining the volume of said solution in contact with said goods substantially the same;

d. rinsing said goods with water to wash said aqueous solution therefrom; and

e. drying said goods.

2. The process as set forth in claim 1 wherein said process includes the steps of maintaining said solution in a plurality of containers and successively immersing said goods into the solution in different ones of said containers.

3. The process as set forth in claim 2 wherein the portion of each of said containers in contact with said solution is glass.

4. The process as set forth in claim 2 wherein the portion of each of said containers in contact with said solution is selected from the class of plastic and polymeric materials.

5. The process as set forth in claim 1 wherein said hydrogen peroxide is electronic grade.

6. The process as set forth in claim 1 wherein said water of said solution is selected from the group consisting of deionized and distilled water.

7. The process as set forth in claim 1 wherein said solution further includes a fluorescent whitener.

8. The process as set forth in claim 1 wherein said solution pH is in the range of 10.5 to 13.5.

9. The invention as set forth in claim 8 wherein said pH is about 11.5.

10. The process as set forth in claim 2 wherein a portion of the solution in each of said containers is continuously removed from, filtered and returned to said containers. 

1. A CONTINUOUS PROCESS FOR SCOURING, DESIZING AND BLEACHING COTTON GREIG GOODS COMPRISING THE STEPS OF: A. IMMERSING SAID GOODS IN A DEIONIZED WATER BATH TO REMOVE IMPURITIES FROM SAID GOODS, B. IMMERSING SAID GOODS FOR A TIME SUFFICIENT TO ACHIEVE COMMERCIAL BRIGHTNESS BUT LESS THAN ABOUT THREE AND ONE-HALF MINUTES IN AN AQUEOUS SOLUTION HAVING A TEMPERATURE IN THE RANGE FROM 160*-212*F AND CONSISTING OF FROM 1 TO 10 PERCENT BY VOLUME HYDROGEN PEROXIDE WATER AND SUFFICIENT HYDROXIDE TO ADJUST SAID SOLUTION TO A PH IN THE RANGE FROM 10-14, SAID SOLUTION BEING SUBSTANTIALLY FREE FROM HEAVY METAL IONS AND MAINTAINED OUT OF CONTACT WITH ALL METALS WHILE GOODS ARE IMMERSED THEREIN, C. CONTINUOUSLY CYCLING A PORTION OF SAID SOLUTION THROUGH A FILTRATION MEANS TO REMOVE SOLID IMPURITIES THEREFROM WHILE MAINTAINING THE VOLUME OF SAID SOLUTION IN CONTACT WITH SAID GOODS SUBSTANTIALLLY THE SAME D. RINSING SAID GOODS WITH WATER TO WASH SAID AQUEOUS SOLTION THEREFROM, AND E. DRYING SAID GOODS.
 2. The process as set forth in claim 1 wherein said process includes the steps of maintaining said solution in a plurality of containers and successively immersing said goods into the solution in different ones of said containers.
 3. The process as set forth in claim 2 wherein the portion of each of said containers in contact with said solution is glass.
 4. The process as set forth in claim 2 wherein the portion of each of said containers in contact with said solution is selected from the class of plastic and polymeric materials.
 5. The process as set forth in claim 1 wherein said hydrogen peroxide is electronic grade.
 6. The process as set forth in claim 1 wherein said water of said solution is selected from the group consisting of deionized and distilled water.
 7. The process as set forth in claim 1 wherein said solution further includes a fluorescent whitener.
 8. The process as set forth in claim 1 wherein said solution pH is in the range of 10.5 to 13.5.
 9. The invention as set forth in claim 8 wherein said pH is about 11.5.
 10. The process as set forth in claim 2 wherein a portion of the solution in each of said containers is continuously removed from, filtered and returned to said containers. 